Bullet Train (BT-80) Road Bike

Discussion in '2 Stroke Bicycle Engines & Kits' started by s1rvr15, Jan 6, 2017.

  1. s1rvr15

    s1rvr15 Member

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    Hey, everyone! Given that there is still very little information out there about these kits (cannonballs2 being the only other user I've seen actively posting anything on them), I'd like to share my build.

    I have desecrated, er... revitalized a 1985 Trek 400 road bike by putting flat bars on it, and removing the shifters and rear derailleur. Oh yeah, also the huge (and I mean huge, this thing is incredibly wide) engine bolted to the frame. As a first note, if you're going to use a older chromoly/steel road bike frame, I would not go smaller than a 56cm or equivalent, you'd have to do some modifications to the wiring to get a 54cm or smaller frame to work. Note you may have to shim out the frame for the junction box or chain tensioner, though the engine itself along with the fuel tank and battery should mount up just fine.

    On the subject of old road bikes, make sure you have decent wheels and spokes. My 30+ year old spokes began to snap from the torque this engine provides, if you're gonna go with 27" wheels, try to steal some off of a Schwinn Continental, those wheels are tanks. The front wheel doesn't matter as much as the rear wheel, it doesn't bear as much weight or nearly as much torque.

    I was originally skeptical (and rightly so) of the battery mounting location under the bottom bracket, but it seems to be okay, but my eagerness to ride meant that I lost a bolt on the front mount which caused my battery to drag along the ground for about 100 feet, but the plastic casing stayed in place and kept it intact, thankfully. If you want to lengthen the wires, you can (and probably should) mount it inside of its case in a bag on a rack, much better in my opinion. You could also go the route cannonballs2 went and use a hobby shop lipo battery, which is smaller and lighter but still turns over the engine just the same.

    Contrary to what Bikeberry will tell you, your kit will come with a 48 tooth sprocket, not a 44. I recommend downgearing to a 44 at the least, this thing has more than enough bottom end to do it. I run a 27" wheel and am thinking about going down to a 41 from my current 44.

    The electric start works, and it works very well. Today the high was 5F where I am, and with any choke whatsoever, it would not start. It started right up like it was 105F out.

    With any motorized bike, mirrors and lights are your friend. The nice thing about this kit is the battery is way more than it needs to be, so you could easily rig up a very nice headlight, taillight (with brakelight functionality if you could find or rig up a switch), turn signals, and even horn. I plan to rig up turn signals and a horn, I will update once I get around to that.

    Included are some totally 100% non-sarcastic wonderful quality photos of my build. If you have any questions about the kit, feel free to post them here, or read cannonball's thread linked below; I'm also sure he wouldn't mind people asking questions there, either.

    cannonball2's thread: http://motorbicycling.com/showthread.php?t=62224



    Image links because they fail to upload as attachments and I don't wanna kill somebody's web browser by loading them all at once:

    http://i.imgur.com/IqLhc0b.jpg

    http://i.imgur.com/iuJV09w.jpg

    http://i.imgur.com/SnWKEy2.jpg

    http://i.imgur.com/3rjNOAO.jpg

    http://i.imgur.com/HULbRY0.jpg

    http://i.imgur.com/Dgpn5Cs.jpg
     
  2. cannonball2

    cannonball2 Active Member

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    Great write up!

    Need a 36 spoke fixie rim. I built a bike from a Walmart fixie($99).

    Had stout wheels and frame.
     
  3. s1rvr15

    s1rvr15 Member

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    Thanks! Either going to salvage a tougher 27" wheel from one of the bikes we have laying around where I work, or get a 700c wheelset and some long sidepull brakes.
     
  4. Kartooo

    Kartooo Member

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    i get rid of the frt derailleur and controls then just leave it in the middle sprocket or whatever you choose. then toss the frt derailleur controls and pick a gear on the rear cassette you like by using a short fixed cable to keep it there. i like it geared looow to get me accross busy intersections...
     
  5. s1rvr15

    s1rvr15 Member

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    My plan is to remove the crank and use a threaded rod with nuts and washers to attach some BMX pegs and use those for footpegs, and remove the front derailleur and rotate the exhaust so I don't burn my foot.
     
  6. Kartooo

    Kartooo Member

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    that is a WIDE engine for sure and needs a WIDE crank
     
  7. crassius

    crassius Active Member

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    not sure about removing pedals and having no way to get home when it fails

    if I recall correctly, it was kcvale that had one & both pull start & electric died with no repair parts available anywhere
     
  8. s1rvr15

    s1rvr15 Member

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    No way I'd be able to pedal an 80lb+ bike very far anyway, walking is the easier way to go for me.

    And I dunno what happened to his, but mine came with a whole ton of spare parts, and Bikeberry said they expect their first parts shipment to come in sometime this month, so I'm not deeply worried. I'm honestly more worried about my bike than the engine.
     
  9. s1rvr15

    s1rvr15 Member

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    Update: replaced the stock "Great Master" spark plug with an NGK B5HS. made a noticeable difference in throttle response. Leaned out the mixture by moving the clip one slot on the needle, and it was definitely too lean, gonna stick to the stock jetting and second notch from the top on the needle, it works in this weather. Replaced all nuts with nylon locknuts, no more things vibrating loose. Going to try and find me a tachometer, turn signals, switch, and relay on the cheap if I can. Probably also going to experiment with a 41T sprocket, lessen out the vibration at road speeds (25-35mph).

    One thing about this engine, it sounds much throatier than the standard HT/CG engine, more rumble and less whine.
     
  10. TheNecromancer13

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    If you want a nice 700c rear wheel, I've got one hanging in my garage that I had on my old motorized road bike, double walled rims, 36 thick spokes quad laced, disc brake hub, super sturdy. I'll sell it to you cheap if you're interested, I have no use for it.
     
  11. s1rvr15

    s1rvr15 Member

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    Thank you for the offer, but I already have wheel plans in place. My idea is to use this for now, then use the deals I get through Trek to get a 520 frame and some nice 700c disc wheels (along with bars and stem), then use my Shimano deals for some nice hydraulic disc brakes and rotors; gonna transfer this engine kit over to that bike when the time comes.
     
  12. scratchbuilder

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    You have phone...load pics right from your phone. All I use is windows 8.1 Nokia. But, I'm not able to see your pics.
     
  13. s1rvr15

    s1rvr15 Member

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    I tried that, but my phone is unfortunately on the fritz, screen likes to randomly stop working.

    As far as my build goes, I swapped the ground wire for a longer and thicker wire (4 gauge, 40") and relocated my battery to my bag on my rack. I found that by routing the positive wire along the top tube, it was just long enough to reach my new battery location without having to replace or lengthen it.

    I'll take some pictures tomorrow, too cold and dark right now. Supposed to be warm enough to get this small amount of snow (probably not even measurable) off the roads, hopefully I'll get a window where I can ride before it's supposed to rain.
     
  14. cannonball2

    cannonball2 Active Member

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    How the build/BT80 going?

    What type of oil are you running in the gear case?
     
  15. s1rvr15

    s1rvr15 Member

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    The bike is good. I'm less good. Took a spill yesterday and broke my arm/wrist pretty good. In a cast until surgery next week.

    I run 10w30 and it seems to work.
     
  16. Kartooo

    Kartooo Member

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    aw crap, sorry to hear that.
    takes a while for bones to heal.
    hopefully the pain isn't too bad.
     
  17. s1rvr15

    s1rvr15 Member

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    Thanks to the wonders of oxycodone, the pain is manageable, haha. The thing that kills me is I can't ride for at least 8 weeks.
     
  18. cannonball2

    cannonball2 Active Member

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    Wow really sorry to hear about this! Really sucks!

    Wish you a mega faster than normal recovery!
     
  19. s1rvr15

    s1rvr15 Member

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    Thank you. I'm hoping surgery goes perfectly and I can get back in the saddle ASAP.
     
  20. fasteddy

    fasteddy Active Member

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    That's rotten luck for sure. Hope you heal quickly and well.

    Steve.
     

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